/*
 * Copyright (C) 2013 Square, Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package com.squareup.picasso;

import android.graphics.Bitmap;

/**
 * A memory cache for storing the most recently used images.
 * <p/>
 * <em>Note:</em> The {@link Cache} is accessed by multiple threads. You must
 * ensure your {@link Cache} implementation is thread safe when
 * {@link Cache#get(String)} or
 * {@link Cache#set(String, android.graphics.Bitmap)} is called.
 */
public interface Cache {
	/** Retrieve an image for the specified {@code key} or {@code null}. */
	Bitmap get(String key);

	/** Store an image in the cache for the specified {@code key}. */
	void set(String key, Bitmap bitmap);

	/** Returns the current size of the cache in bytes. */
	int size();

	/** Returns the maximum size in bytes that the cache can hold. */
	int maxSize();

	/** Clears the cache. */
	void clear();

	/** A cache which does not store any values. */
	Cache NONE = new Cache() {
		@Override
		public Bitmap get(String key) {
			return null;
		}

		@Override
		public void set(String key, Bitmap bitmap) {
			// Ignore.
		}

		@Override
		public int size() {
			return 0;
		}

		@Override
		public int maxSize() {
			return 0;
		}

		@Override
		public void clear() {
		}
	};
}
